In recent years the use of endoscopic surgical procedures has increased. Endoscopic surgical techniques have enabled the simplification of many surgical procedures which previously required extensive surgery with its attendant risks and problems. Often operations which ordinarily might take many hours and extensive recuperation periods may be reduced to relatively short duration with only brief recuperation required. For example only, endoscopic surgical procedures are used widely in diagnosis and surgical treatment for joint ailments, such as knee surgery.
In an endoscopic surgical procedure a small incision is made through which a rigid endoscope is inserted. The endoscope includes an optical system having an objective lens at its distal end and viewing optics at its proximal end so that the surgeon may inspect visually that part of the body into which the endoscope has been inserted. Light for illumination of the region to be viewed is transmitted through optical fibers which extend through the endoscope to its distal end. The proximal end of the endoscope typically is provided with an eyepiece to facilitate handling and viewing by the surgeon. The endoscope may be used to make a diagnostic inspection as well as during a corrective surgical procedure. When used in a corrective procedure the surgery is performed by making another small incision nearby through which a guide tube is inserted. Miniature surgical instruments then are passed through the guide to the internal surgical field. The surgeon manipulates the miniaturized instruments while simultaneously viewing through the endoscope the surgical field within the patient's body
Direct viewing through the eyepiece of the endoscope typically requires that the surgeon must bend over for extended periods of time with great strain and fatigue both to eyes and back. In an effort to overcome this fatiguing effect it has become increasingly common to connect a video camera to the eyepiece of the endoscope and to observe the surgical field on a video monitor connected to the video camera. Thus the surgical procedure may be seen magnified substantially on a video monitor, the surgeon can perform the surgery comfortably with less fatigue, and the surgery can proceed faster and more efficiently.
In order to connect the endoscope to the video camera an intermediate coupling device is used. Typically the coupling device has a fitting at its rear end which attaches to the video camera. The front end of the coupler typically has a coupling ring which receives and grips the endoscope by the eyepiece. The couplers typically have intermediate lenses which focus the image from the endoscope optics on the focal plane of the camera. The coupling ring engages the endoscope eyepiece in a manner which enables the endoscope to be rotated, by its eyepiece, in the coupling ring. That enables the endoscope and camera to be rotated relative to each other, either to reorient the image on the video monitor or to redirect the field of view within the patient's body. Typically the coupling devices also enable the endoscope to be detached from the coupling so that endoscopes may be changed. In that regard, it is not uncommon for some procedures to require the use of a number of endoscopes, each having special optical or structural characteristics for different purposes. Sometimes fogging of the optics requires a change in endoscopes so as to maintain optical clarity during the procedure.
While the foregoing devices used in video endoscopy have been significant advances and have simplified many surgical procedures, they are not free of difficulties. For example, although it is preferable that the devices be as light and easily manipulable as possible, the couplers tend to be relatively bulky and cumbersome. This presents some difficulty, particularly with smaller diameter, relatively fragile endoscopes which, in some instances, may be as slender as two millimeters diameter. Such a slender endoscope may be damaged, such as by bending, from the weight of a comparatively heavy coupler. Additionally, the awkward, bulky type of coupler which has typified the prior art does not provide the surgeon with as comfortable and sensitive a feel as he might have if the instrument were lighter and less awkward to manipulate.
Also among the difficulties presented with the prior couplers is that they often entrap liquid or water and tend to fog up during the surgical procedure. The liquid tends to become entrapped during the sterilization procedure which, typically, requires total immersion of the endoscope, coupler and video camera, as a connected unit, in a bath of sterilization liquid such as a gluteraldehyde based solution. It is common, with the prior coupling devices for some of the liquid, even in minute quantities, to seep in between the eyepiece and the coupler, ultimately resulting in fogged up optics. Often the fogging does not begin to appear until the surgical procedure is well underway.
Another common difficulty with the prior devices is that the coupling ring which grips and engages the endoscope eyepiece does not do so in a manner which permits a smooth and steady feel when the endoscope is rotated relative to the coupler. Often the coupling rings tend to bind up or present varied resistance during rotation.